Bug-A-Boo is a web based bug reporting system for Linux. It runs on any web server providing CGI functionality. Bug-A-Boo does not need any database server but brings along its own local tables it accesses with tdbengine.

The Bug Genie is an open source issue tracking system, built on open source technology. It enhances your development process, by offering an advanced tool to manage bug reports, feature requests and user feedback for your products.

BugTracker.NET is a free, open-source, web-based bug or customer support issue tracker written using ASP.NET, C#, and Microsoft SQL Server (or its free cousin, SQL Server Express). It is in daily use by thousands of development and support teams around the world.

Bugzilla is an open source Defect or Bug Tracking System. Defect Tracking Systems allow individual or groups of developers to keep track of outstanding bugs in their product effectively. Bugzilla is used by all projects from the Mozilla foundation. Most commercial defect-tracking software vendors charge enormous licensing fees. Despite being free, Bugzilla has many features its expensive counterparts lack. Consequently, Bugzilla has quickly become a favorite of thousands of organizations across the globe. Bugzilla helps track bugs and code changes; communicate with teammates; submit and review patches; manage quality assurance (QA). Bugzilla can help you get a handle on the software development process. Successful projects often are the result of successful organization and communication. Bugzilla is a powerful tool that will help your team get organized and communicate effectively.

Eventum is a user-friendly and flexible issue tracking system that can be used by a support department to track incoming technical support requests, or by a software development team to quickly organize tasks and bugs. Eventum is used by the MySQL AB Technical Support team, and has allowed us to dramatically improve our response times.

itracker is a true open source issue tracking system licensed under the LGPL license. itracker is built using Java enterprise technology. itracker is a professional, easy to use, open, easy to integrate, fast, modular, customizable and scalable solution for all kind of projects.

JTrac is a generic issue-tracking web-application that can be easily customized by adding custom fields and drop-downs. Features include customizable work-flow, field level permissions, e-mail integration, file attachments and a detailed history view.

Kwok Information Server is an open source IT management system. Kwok Information Server, utilizing open source software such as Java, Tomcat and PostgreSQL, provides a centralized system for managing/tracking hardware inventory, software licenses, issues, service contracts, and vendor contacts.

Mantis is an easily deployable, web based bug tracker to aid product bug tracking. It requires PHP, MySQL and a web server. Some of the features include Simple User Experience; Web Based; Supports any platform that runs PHP (Windows, Linux, Mac, Solaris, AS400/i5, etc); Available in 68 localization; Customizable Issue Pages; Multiple Projects per instance; Support for Projects, Sub-Projects, and Categories.; Users can have a different access level per project.
MantisBT features can be enhanced with the MantisBT plugin system that allows extension of MantisBT through both officially maintained and third party plug-ins.
Detailed information on how to use git with MantisBT can be found in the Mantis Bug Tracker Developers Guide.

oops-easytrack is a Bug Tracking System, implemented as a lan-based and a web-based version. Bugs are created, modified, logged or searched. Users, projects,components and releases can be administrated. Reports of 4 types may be generated.

Redmine is a flexible project management web application. Written using Ruby on Rails framework, it is cross-platform and cross-database. Redmine is open source and released under the terms of the GNU General Public License v2 (GPL). Some of the main features of Redmine are Multiple projects support; Flexible role based access control; Flexible issue tracking system; Gantt chart and calendar; News, documents & files management; Feeds & email notifications; Per project wiki; Per project forums; Time tracking; Custom fields for issues, time-entries, projects and users; SCM integration (SVN, CVS, Git, Mercurial, Bazaar and Darcs); Issue creation via email.

Trac is an enhanced wiki and issue tracking system for software development projects. Trac uses a minimalistic approach to web-based software project management. Our mission is to help developers write great software while staying out of the way. Trac should impose as little as possible on a team's established development process and policies. It provides an interface to Subversion, an integrated Wiki and convenient reporting facilities. Trac allows wiki markup in issue descriptions and commit messages, creating links and seamless references between bugs, tasks, changesets, files and wiki pages. A timeline shows all project events in order, making the acquisition of an overview of the project and tracking progress very easy.

Vermis is an Open Source issue tracker and project management tool for software developers and project managers that has been created for improving quality of code, efficiency and speed of development.

WebIssues is an open source, multi-platform system for issue tracking and team collaboration. It can be used to store, share and track issues with various attributes, comments and file attachments. It is easy to install and use but has many capabilities and is highly customizable. WebIssues offers much greater possibilities of customization than most traditional issue tracking systems. It allows tracking bugs, tickets, tasks, requests and any other information, with the same flexibility as a spreadsheet, where columns can be freely added and modified. However, WebIssues allows many people to work simultaneously, maintains the full history of changes, controls the permissions for different areas of the system, and makes it possible to discuss and exchange information about individual issues and to attach files to them. WebIssues provides access by both the web browser and a desktop client application, which natively supports Windows, Linux and OS X. The desktop client makes everyday work with the system easier and faster, by providing comfortable user interface, instant search and convenient editing. The web client makes it possible to access the system from any location at any time.